A wiring board has been known that includes an insulating layer covering a wiring layer, where an opening is formed in the insulating layer to expose part of the wiring layer and a metal layer of nickel or the like is formed on the exposed part of the wiring layer in the opening.
A semiconductor chip is mounted on such a wiring board, so that a semiconductor package is formed. In this case, solder is provided on an upper surface of the metal layer exposed inside the opening of the wiring board, so that the upper surface of the metal layer and an electrode pad of the semiconductor chip are joined with the solder. (See, for example, Japanese Laid-Open Patent Publication No. 2002-290022.)